Various retinal analogs will be synthesized, irradiated with monochromatic light, and the various double bond isomers will be separated by high-speed liquid chromotography. After structure determination, the respective pure retinals will be tested for rhodopsin formation with opsin. The synthetic retinals will be tailored so that collectively they will give a clearer definition of the steric and chiral criteria of the opsin binding site and cavity. A (14-C14)-retinal is being incorporated into rat retina for the purpose of clarifying the turnover rate, etc. of retinal in vivo. The mild non-photochemical and non-thermal bleaching process of rhodopsins utilizing methylene chloride will be applied to a variety of visual pigments including bacteriorhodopsin. The yellow fluorescent pigment which accumulates in the human eye lens and which may have a direct bearing on senile cataract is also under study. BIBLIOGRAPHIC REFERENCES: Allenic Retinals and Visual Pigment Analogues, K. Nakanishi, A.P. Yudd, R.K. Crouch, G.L. Olson, H.-C. Cheung, R. Govindjee, T.G. Ebrey, D.J. Patel, J. Amer. Chem. Soc., 98, 236 (1976). Micellar Effects on the Photochemistry of Rhodopsin, W.H. Waddell, A.P. Yudd, K. Nakanishi, J. Amer. Chem. Soc., 98, 238 (1976).